reproductive endocrinology - guyton ch. 80, 81 (powerpoint)

Copyright © 2006 by Elsevier, Inc.

Male Reproductive System

Figure 80-1Guyton & Hall


Cross section of the seminiferous tubule and stages of sperm

development

Figure 80-2Guyton & Hall


hypothalamus

gonadotropin releasing hormone

ant. pituitaryLH FSH

Leydig cells Sertoli cells

androgens

growthfactors

inhibin

estrogens

androgenbindingprotein

spermatogenesis

aromatization

peripheralaromatization

Hypothalamic-pituitary-gonadal axis

(function 1)

(function 2)

pulsatile -- 8-14/24h

pulsatilepulsatile

_

_

_

+

_



Tissues Producing Androgens

cholesterol

androstenedione

testosterone

DHT E2

testisadrenal

peripheral tissues

5-reductase CYP 19


Different Stages of Male Sexual Function:Plasma Testsosterone and Sperm Production

Figure 80-9; Guyton & Hall


Cell Divisions DuringSpermatogenesis

Figure 80-3;Guyton & Hall


Differences between Spermatogenesis and Oogenesis

1. In females, mitotic proliferation of germ cells occurs prior to birth. In males, spermatogonia proliferate

only after puberty.

2. In female, meiotic divisions of primary oocyte produces only one secondary oocyte. In male, meiotic divisions ofprimary spermatocyte produces 4 maturespermatozoa

3. In female, second meiotic division is completedonly upon fertilization. In male, the products ofmeiosis (spermatids) undergo substantial differentiation in the maturing process.


Figure 81-2; Guyton & Hall

Internal structures of the Uterus, Ovary and a Fallopian Tube.


Fundamental reproductive unit = single ovarianfollicle, composed of one germ cell (oocyte), surrounded by endocrine cells


Menstrual cycle – controlled by gonadotropins,gonadal hormones

Ovarian cycle – follicular phase – avg 15 d (range, 9-23 days)ovulationluteal phase – 13-14 d – less variable than follicular

Endometrial cycle – menstruation, proliferative and secretory phases


1 4 14 28

FSHLH

ovulationLHsurge

proliferative phase

(11 d)EndometrialCycle: menstrual

secretory phase (12d)

OvarianCycle: follicular phase

LH surge lasts 48 h

IncGnRHbursts

FSH and LH in the Follicular phase



1 4 14 28

FSH

LH

ovulationLHsurge

Proliferative phase(11 d)

EndometrialCycle: menstrual

Secretory phase (12d)

estradiolfeedback--GnRH

neg

OvarianCycle: follicular phase

Increase in estradiol to stimulate LH surge. Then estradiol has Negative feedback on GnRH to reduce LH, FSH.



Figure 81-4;Guyton & Hall

Stages in follicular growth and ovulation.


Contraception

Rhythm method: if periodicity of menstrual cycle is 28 d, then ovulation should be day 13-15: temp decreases and then increases slightly following ovulation. Also, consistency of mucus discharge from the vagina changes. Now, ovulation kits available.

Oral, patch contraceptives: ethinyl estradiol, mestranol; gestodene, norgestimate – decr. androgenic effectssuppress GnRH, FSH, LH – prevent LH surge (no ovulation)progestins: cervical mucus thickens, inhibit motility – decr.transport of ova and sperm – endometrium not conducive to implantation


Implant contraceptives: norprogestins: “Norplant” lasts 5 yrs

Depoprovera – last 3 mos – inhibits ovulation, implantation

Intrauterine device – IUD – spermicidal effect caused by sterile inflammatory reaction – secondarily prevents implantation of zygote

Barrier methods: diaphragm with spermicidal jelly, condoms

Postcoital contraceptives: RU 486 – not approved for use “Plan B” – oral contraceptives used within 72 hrs of unprotected intercourse

Tubal ligation

Vasectomy



Menopause

Defn: obsolescence of ovaries, no estradiol production, ovaonly occasional secondary follicle, few primary follicles

Occurs at 51.4 yr of age (average)

Due to reduction in estrogen, low levels of inhibin, no negative feedback of LH and FSH; therefore, high levels LH and FSH

Can occur naturally, due to surgery or as a result of chemotherapy


Rat Data

• Females – – Average overall weight gain = 20.3%– Average weight gain during HRT on E1 = 8.1%– Average weight gain during HRT on E2 = 5.9%– Average estrous cycle length = 4.2 days – Vag smears with E1 = estrous phase– Vag smears with E2 = diestrous phase

• Males – – Average overall weight gain = 31.2%– Average weight gain during HRT on T1 = 8.2%– Average weight gain during HRT on T2 = 10.8%

reproductive endocrinology - guyton ch. 80, 81 (powerpoint)

Documents

fsh lh ovulation lh

d ovarian cycle

d endometrial cycle

average weight gain

proliferative phase

guyton hall stages

average estrous cycle

periodicity of menstrual